Electric switch for controlling a number of magneto circuits



y 1942- F. R. F. RAMSAY I I 2,282,747

ELECTRIC SWITCH FOR CONTROLLING A NUMBER OF MAGNETO- CIRCUITS Filed March 8, 1941 Fig. 2.

A c c c c Inventor F. RF. RAMSAY A ttomey Patented May '12, 1942 ELECTRIC SWITCH FOR CONTROLLING A NUMBER OF MAGNETO CIRCUITS Frank Raymond Faber Ramsay, London, Eng land, assignor to D. Napier.& Son Limited, London, England, a. company of Great Britain Application March 8, 1941,, Serial No. 382,442

In Great Britain March 14, 1940 I 7 2 Claims. This invention: relates to electric switches more particularly for controlling a number ofmagnetos associated with an internal combustion engine. I In the case of large internal combustion engines for aircraft a number of magnetos may be provided, for example each cylinder will have two sparking plugs whilst separate magnetos may be provided for. two different banks of cylinders making four magnetos in all. One object of the present invention is to provide a form of multiple switch by which all the magnetos can be switched off simultaneously but if desiredcertain combinations of magnetos can be switched ofi momentarily without theothers for testing purposes. It is also desirable that the, switch should be of small frontal area so as not to cupy a large space on. the already'crowded panel of the aircraft.

. According to the present invention a switch for controlling a number of magnetos to switch them off all together or separately comprises two op erating members, namely a selecting member or handle for preselecting the magnetos to be connected to earth, and a connecting member or handle for causing the connection to be effected, wherein the two members are so interlocked and spring-biassed that the connecting handle will only remain in the off position when released if the selecting handle is so placed that all the magnetos are thereby switched off.

.aconvenientlyflthe selecting handle serves ;to

rotatev a barrel switch mounted behind and per; pendicular to a front panel so as to present 'a small frontal area. The barrel of this switch may be arranged to be moved longitudinally by the connecting handle to bring contacts on the barrel into engagement with stationary contacts or fingers.

The connecting handle-is preferably in the form of a dolly or lever resembling that of an ordinary tumbler switch so that pilots accustomed to an ordinary tumbler switch will be able to switch off the magnetos in the customary manner. The connecting, handle may, for example, act through a toggle mechanism to move the barrel of the barrel switch longitudinally against the action of a spring, and may be interlocked with the selecting handle by means which prevent the toggle from reaching'the dead centre position, so that when so interlocked it springs back to the on position when released.

It is desirable that a single operating handle should serve to switch oif all the magnetos in the ordinary way but at the same time the magnetos should not be connected together until they are all switched off by being connected to earth.

,The invention may be carried into effect in various waysbut one particular construction is illustrated by way of example in the accompanying drawing, in which Figure 1' is a front elevation, and Figure 2 is a sectional side elevation.

The switch illustrated is intended for an H- section engine having a dual ignition system using a front and a rear sparkingplug in each cylinder. Eachhalf of the ignition system, i. e; the front plugs or the rear plugs, is supplied by a twin magneto or pair of magnetos, one of which supplies the top banks of cylinders whilst the other supplies the lower banks. Moreover for testing purposes it should be possible to switch off the magnetos supplying the front sparking plugs of all the cylinders or those supplying the back sparking plugs of all the cylinders or for one magneto to be switched off at a time. On the other hand; the switch should be arranged to prevent botnmagnetos of the top cylinders or both magnetos of the bottom cylinders from being switched off-unless all four magnetos are switched off and should also prevent the switch being leftsin such a position that only one or .two; of themagnetos are switched off.

The switch illustrated. comprises a casing A having .a removable topcover AI and a front panelB Mounted in the lower portion of the casing-is .-a spindle Cl carrying an insulating barrel C-whi ch is, provided with conducting segments C2. The barrel switch is adapted to ro-, tate ab out itsaxis in the hexshaft shown and also-,move longitudinally thereon, and is connected to a-selecting handle D on the front panel by which it can be rotated. The barrel C is provided with a circumferential groove C3 engaged by the lower end of a lever E mounted on a fixed pivot El and connected by a link E2 to the arm F! of a bell-crank F which projects through the front panel B and constitutes the connecting handle. This handle resembles the dolly or lever of an ordinary tumbler switch and the arm Fl and the link E2 constitute a toggle by which the barrel C is moved longitudinally when the lever F is actuated.

The arm E2. is provided with a spring G which tends to move the barrel towards the front panel so that the barrel will only remain in its off position, remote from the front panel, when the lever F is depressed so far that the toggle passes over its dead centre. The selecting handle D is provided with any suitable means for holding it in a number of predetermined angular positions and carries a disc DI having a slot or notch D2 with which a projecting arm F2 on the operating lever can engage only when the selecting arm and disc DI occupy the position shown in Figure 1. Thus unless the selecting member is in that position, the arm F2 will engage the edge of the disc DI when the lever F is depressed and so prevent the toggle from moving over its dead centre, though moving the cylinder to its second position. Hence directly the lever F is released, under the action of the spring G it will return to the raised position shown in Figure 2 and thus return the barrel C to its first or oil position.

Mounted within the upper portion of the casing is an insulated member H from which extend a number of blade contacts J engaging the surface of the barrel C. The barrel carries a number of conducting segments G2 which are flush with its surface and are all connected together to the spindle Cl and thence by means of a flange 04 on the spindle to a spring contact K connected to earth. The segments C2 are soar-ranged on the barrel that when the barrel is in the position shown in Figure 1, each segment is longitudinally spaced from the adjacent blade contact J, these blades and contacts being staggered in relation to one another. When however the barrel 0 is moved longitudinally away from the front panel by depressing the lever F, the segments C2 are brought into alignment with the blade contacts J and this occurs whether or not the connecting lever F is moved downwards to the full extent (which can only occur when the 1 will be connected together and hence the magnetos will be connected to earth and switched off. By rotating the handle D in a clockwise direction only the magnetos of the front sparking plugs are switched off. Thus if the handle D is moved so that the index FTB' lies immediately below the lever F, both top and bottommagnetos are switched off. If it is moved into the second position so that the index -FI- occupies the central position below the lever F, only the magneto of the front topcylinder is switched off, and in the third position when the index FB lies immediately below the lever F, only the magneto of the bottom cylinders is switched off. Similarly moving the handle in an anticlockwise direction so as to bring the markings R'IB, RT or RB into the central position below the lever F, produces corresponding results on the magnetos of the rear sparking plugs.

In addition to the contacts J required for switching off the magnetos, one or more further contacts J l with corresponding segments C5 may be provided for associated auxiliary devices. For example, a set of contacts may be connected in the circuit of the under carriage warning light and arranged to break this circuit only when all the magnetos are switched off. In the same way for other purposes segments may be provided which make or break the circuit only when the barrel occupies a certain angular or axial position. For example, a double width segment of short angular extent may be provided to close a circuit whenever the barrel is rotated to a predetermined angular position whether or not all the magnetos have been actually switched off.

It will be appreciated that the construction described has the advantages referred to above. The frontal area of the switch is quite small, the form of the connecting handle resembles that of an ordinary tumbler switch, the magnetos are not connected together until they are connected to earth, only the desired combinations of magnetos can be switched off, and no magneto can be left switched off unless they are all switched ofl.

What I claim as my invention and desire to secure by Letters Patent is:

1. An electric switch for controlling a number of contacts having means to switch them all off together or separately, comprising-a movable barrel having contacts, an operating member for rotating the barrel including a disc provided with a notch and forming a preselecting member for the contacts to be connected for efiecting contact, a connecting member including a manually operated lever having a stop, a toggle mechanism and a spring connected therewith whereby the lever will be returned to its initial position directly it is released unless. the stop on said lever registers with the notch in said disc, thus giving the switch the property of being both selfreleasing and self-locking in accordance with the position of the preselecting member. 2. A switch mechanism as set forth in claim 1, including a relatively narrow elongated'casing with means at one end to permit securement to an instrument board or the like.

FRANK RAYMOND FABER RAMSAY. 

